US4339352A - Sorptive clay composition and method of manufacture - Google Patents
Sorptive clay composition and method of manufacture Download PDFInfo
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- US4339352A US4339352A US06/238,272 US23827281A US4339352A US 4339352 A US4339352 A US 4339352A US 23827281 A US23827281 A US 23827281A US 4339352 A US4339352 A US 4339352A
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- clay
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- volatile matter
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
- B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
- B01J20/12—Naturally occurring clays or bleaching earth
Definitions
- the present invention relates to clays having sorptive properties.
- Such clays are known collectively as fuller's earth and are characterized by the fact that they absorb water, oils and greases and are capable of removing undesirable constituents, such as dyes and coloring matter from aqueous solutions and from oils. Included in this group of clays are attapulgite, sepiolite, and bentonites.
- Attapulgus clay hereinafter referred to as attapulgite
- a comparatively hard granular material of high sorptive power is required which will not disintegrate on contact with water.
- Important uses of this type are materials used to absorb water and mixtures of oil and water from floors, materials used for animal bedding, commonly called pet litter and materials used as carriers for agricultural products. In many cases it is also desirable that the material should exhibit a substantially neutral pH in water.
- Natural Attapulgus clay does not have sufficient sorptive properties or sufficient hardness for commercially practicable purposes and it is customary to apply various degrees of thermal activation to the clay in order to develop the required properties depending upon the purpose for which the product is to be used.
- the effect of thermal activation on Attapulgus clay is described in an article by W. S. W. McCarter, et al "Thermal Activation of Attapulgus Clay", Industrial & Engineering Chemistry, Vol. 42, No. 3 March 1950, pages 529 to 533.
- Sorptive properties and hardness adequate for some applications are obtained by heating the clay to a temperature of 400° to 500° F.; the product of this thermal activation retains much of the water of constitution, typically 15 to 18% as measured by volatile matter at 1200° F.
- activated clays have little resistance to disintegration by contact with water which converts them to a sludge of fine particles.
- Such materials are not, therefore, practicable for many applications, such as floor absorbents and pet litter.
- the clay In order to confer the necessary resistance to water, the clay must be activated at a higher temperature, typically 800° to 1000° F. which results in loss of most of the water of constitution, the product containing 5% or less of volatile matter at 1200° F.
- clays activated at these higher temperatures have the required sorptivity, hardness and resistance to water they are more costly to produce, particularly because of the greater energy requirements to raise the temperature and to drive off the water of constitution.
- the essence of the present invention resides in treating a sorptive clay with an alkali metal silicate, preferably sodium silicate, and heating the treated clay to expel free moisture and a proportion of the combined water such that the product contains less than 25% of volatile matter at 1200° F.
- the clay may also be treated with an acid in a proportion such that the final product after heat treatment has a pH when slurried with water in the range of about 5 to 10.
- the product has compositions in the range of about 85-99% by weight clay, 1-10% sodium silicate based on volatile-free weight of the clay, and about 0.3-3% acid based on volatile-free weight of the clay.
- a preferred embodiment of the invention comprises a process in which Attapulgus clay is treated with a solution of sodium silicate in which the molecular ratio SiO 2 :Na 2 O is at least 1.5:1 and the heated clay is then activated to increase its sorptive properties by heating to a temperature in the range 300° F. to 700° F. for a sufficient time to reduce the volatile matter when determined at 1200° F. to not more than 25% and preferably to not more than 20%.
- the clay is also treated with an acid selected from the group comprising phosphoric acid, sulphuric acid and water-soluble organic carboxylic acids.
- the amount of acid used is such that the pH of an aqueous slurry of the activated clay lies between 5 and 10, preferably between 6.0 and 9.5.
- the acid is phosphoric acid or acetic acid in amount of about 0.3-3% by volatile-free weight of the clay.
- the acid may be added to the clay before heat treament or after heat treatment.
- a sorptive mineral suitable for practice of the present invention is Attapulgus clay or Georgia-Florida fuller's earth, which is composed principally of the mineral attapulgite, a crystalline hydrated magnesium aluminum silicate, but which also may contain significant amounts of mineral impurities such as montmonrillonite, calcium carbonate, quartz (silica) and feldspar, and in some cases sepiolite.
- This clay and processing thereof by heat-treatment to obtain special properties are well known in the art. Further detail on processing and resultant properties is disclosed in U.S. Pat. No. 3,953,292 to Burns and U.S. Pat. No. 3,041,238 to Allegrini.
- Heat treated attapulgite clays typically have a surface area of about 80-140 m.
- Attapulgite clay may be calcined by means conventional in the art, for example a rotary calciner. Calcination temperature range from about 400° to 1000° F. in general processing of this clay. Calcination at temperatures in the lower end of the aforementioned range give rise to an attapulgite clay having total volatile matter of about 16%. This clay is known as an RVM grade attapulgite clay and is preferred herein for economic reasons. The higher temperature range calcination gives rise to an attapulgite known as an LVM-grade clay of very low volatile matter of about 5% as produced. Total volatile matter of the clay as used, however, may range up to about 10% as a result of the mineral readily absorbing moisture from the atmosphere.
- the product of the present invention is crushed and screened to size prior to sale and use. Different applications of the product require a different size range to fit the end use. Crushing and sizing may be done in a manner conventional in the art, e.g. by hammermill and screening.
- the product of the present invention may be made by mixing silicate solution and clay in conventional pugging or extrusion devices and subsequently drying, crushing and sizing. Alternatively, silicate solution may be sprayed onto raw clay prior to drying.
- an acid to reduce pH of the product when slurried in water, takes place preferably after thermal treatment (drying). This may occur during the sizing or screening operation or immediately thereafter, wherein acid solution is sprayed onto the claysilicate material on the screens or onto material just exiting from the screens.
- raw Attapulgus clay is mixed with sodium silicate in amounts ranging from 1 to 10% by weight sodium silicate based on the weight of the clay.
- the sodium silicate is applied as an aqueous solution containing 10 to 50% by weight of the clay of sodium silicate in which the molecular ratio SiO 2 :Na 2 O lies in the range 1.7:1 to 2.2:1, although other sodium silicates with different ratios, such as O®-brand and N®-brand sodium silicates may be used.
- the mixture of clay and sodium silicate solution is heated to a temperature in the range 400° F. to 600° F. for a sufficient time to reduce the volatile matter when determined at 1200° F.
- the clay is also treated with 0.3% to 3% of its weight of acetic acid or phosphoric acid, the amount of acid being selected so that the pH of an aqueous slurry of the activated clay lies between 6.0 and 9.5.
- the acid may be added to the clay before thermal activation.
- the thermally activated clay is treated with the acid for reasons hereinafter set forth.
- raw Attapulgus clay is mixed with 2% to 6% by weight of the clay of sodium silicate calculated on a dry basis
- the sodium silicate is introduced into the clay as an aqueous solution containing 10 to 50% by weight of the clay of sodium silicate in which the molecular ratio SiO 2 :Na 2 O lies between 1.7:1 and 2.2:1.
- the silicate solution is added to the clay during mixing in a pug-mill or other suitable equipment.
- silicate solution may be simply sprayed onto clay prior to drying.
- the mixture is heated to a temperature in the range 400° to 600° for a time sufficient to reduce its volatile matter at 1200° F. to a value within the range 8% to 18%.
- This activated clay is then treated with 0.5% to 2.0% of its weight of an 85% by weight aqueous solution of phosphoric acid.
- the thermally activated clay is crushed or milled before being treated with the acid.
- the following examples show how the process of the invention enables activated sorptive clays to be made by heat treatment at the lower temperature yielding products of comparatively high volatile matter.
- the process of the present invention obviates the need for higher temperature thermal treatment to expel additional water, and yields a product with acceptable sorptive properties, attrition resistance and pH suitable for use in wet environments.
- a wet breakdown in the range of about 2-25% an oil absorption in the range of about 60-120% and a water absorption in the range of about 70-170% may be achieved, as determined by experimental tests described hereinafter.
- the product was found to show 92% wet attrition breakdown, oil absorption of 80% and water absorption of 110%.
- the pH of its aqueous slurry was 7.9.
- the material was then further heated to 900° F. for two hours when it lost a further 9.6% by weight.
- the product contained 4% volatile matter at 1200° F. and gave a wet attrition breakdown of 3%, oil absorption of 100% and water absorption of 120%.
- the pH of its aqueous slurry was 7.5. These properties are typical of thermally activated Attapulgus clays sold commercially for use in floor absorbents and pet litter.
- the example illustrates that a thermally activated Attapulgus clay prepared by heat treatment at 525° F. and yielding a product containing 17% volatile matter at 1200° F. has sorptive properties and pH substantially the same as one prepared at 900° F. and having only 4% volatile matter at 1200° F. More importantly, it shows also that the clay prepared at the lower temperature has virtually no resistance to wet attrition, whereas the clay prepared at the higher temperature is almost completely resistant to wet attrition.
- the pH of aqueous slurry was determined by weighing 10 grams of a clay sample into a 250 ml. beaker, adding 90 ml. of distilled water, boiling for about five minutes, cooling and determining the pH electromagnetically (pH meter) with the clay in suspension.
- the oil and water absorption of the clay was determined by placing 20 g. of the clay in a cone-shaped fine wire (60 mesh) screen container, immersing the container and contents in SAE 10 oil or water for twenty minutes, removing the container to drain at room temperature for 20 minutes in the case of water and for one hour in the case of oil. The % oil or water retention was then calculated on the basis of the original sample weight.
- the degree of wet breakdown or the degree of disintegration of the granular sorbent material in water was determined by placing 50 g. of material of a specified size range (obtained by screening) into a 500 ml. beaker, adding 200-250 ml. of water and boiling for about 5 minutes. The resultant slurry is washed over a limiting screen (the smaller sized screen used for the original sample) and dried at about 200° F. The weight by difference is the % breakdown based on the original weight of the sample. Drying must be done carefully so as not to alter the volatile matter content of the clay sample.
- Attapulgus clay sorbents formed by the process of the present invention are shown to be equivalent to LVM heat-treated grades of Attapulgus clay with respect to water and oil absorption and wet breakdown.
- the Attapulgus clay of Example 1 (clay A in Table I below) and another raw Attapulgus clay were mixed with sodium silicate in a pug mill.
- the aqueous sodium silicate solution was 44% concentration by weight containing SiO 2 /Na 2 O ratio of about 1.9, and was added at 4.1% of the weight of the clay which was 4,000 g. in the form of lumps of clay. In some cases small amounts of acid were also added during the pugging operation with the aim of reducing product pH.
- the pugged mixture was thermally activated by heat treatment at 525° F. for 3 hours and subsequently crushed and screened to size (-12+45 mesh). The performance of the product made by this method is summarized in Table I below:
- Clays A and B were samples of Attapulgus clay with slightly different volatile matter content as mined. Clay A had 54.3% volatile matter at 1200° F. wherein Clay B had 49.9%. After identical heat treatment Clay A showed 12-15% volatile matter at 1200° F., whereas Clay B showed 6-10%. These variations are to be expected from natural variability in the clay as mined. The performance of the clays were similar after treatment, however, so that the differences do not substantially affect the performance.
- phosphoric acid which is preferred for its corrosion-preventing ability on iron, was added to the Attapulgus clay-silicate mixture after drying, rather than during the pugging stage as in Example 2.
- Oil and water absorption of samples 36A-36F were comparable to those of Example 2, i.e. about 90-110% oil absorption and about 140-160% water absorption. It can be seen from the above Table II that wet breakdown of corresponding samples in Example 2. Thus the preferred method of adding the acid is subsequent to the drying step rather than during the pugging or mixing operation.
Abstract
Description
TABLE I ______________________________________ EVALUATION OF ATTAPULGUS SORBENT CLAY MADE WITH SODIUM SILICATE AND ACID ADDITION % Added 85% Phos- % % % Acetic phoric Wet Oil Water Clay Acid Acid Breakdown Absorption Absorption pH ______________________________________ A 0.25 -- 10 113 162 9.4 B 0.25 -- 29 102 165 9.3 B -- 1.6 68 96 170 6.8 B -- 0.8 66 108 167 7.8 B -- -- 11 105 144 9.7 ______________________________________
TABLE II ______________________________________ EVALUATION OF ATTAPULGUS CLAY SORBENT CLAY MADE WITH ADDITION OF PHOSPHORIC ACID AND SODIUM SILICATE % Phosphoric % Acid Added Wet Sample Nominal Actual Breakdown pH ______________________________________ 36 A -- -- 18 -- 36 B 0.5 0.21 11 9.7 36 C 0.75 0.63 15 9.5 36 D 1.0 0.70 11 9.3 36 E 1.0 0.88 14 8.6 36 F 1.25 1.04 13 9.2 ______________________________________
Claims (12)
Priority Applications (1)
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US06/238,272 US4339352A (en) | 1981-02-25 | 1981-02-25 | Sorptive clay composition and method of manufacture |
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US06/238,272 US4339352A (en) | 1981-02-25 | 1981-02-25 | Sorptive clay composition and method of manufacture |
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US4339352A true US4339352A (en) | 1982-07-13 |
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US06/238,272 Expired - Lifetime US4339352A (en) | 1981-02-25 | 1981-02-25 | Sorptive clay composition and method of manufacture |
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Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5413978A (en) * | 1993-11-30 | 1995-05-09 | Engelhard Corporation | Catalytically inert particles for blending with petroleum cracking catalyst |
US5935623A (en) * | 1998-01-15 | 1999-08-10 | Milwhite, Inc. | Use of thermally treated clays in animal feeds |
CN1052210C (en) * | 1994-11-06 | 2000-05-10 | 张义纲 | Process for preparing activated bleaching clay from attapulgite clay |
WO2001034295A1 (en) * | 1999-11-12 | 2001-05-17 | Engelhard Corporation | Sorbent, method of making the sorbent, and method of using the sorbent in fixed bed applications |
CN101733076B (en) * | 2009-12-31 | 2011-12-14 | 四川大学 | Modified attapulgite adsorbent for tannery wastewater treatment and preparation method thereof |
CN102806063A (en) * | 2012-09-04 | 2012-12-05 | 中国科学院兰州化学物理研究所盱眙凹土应用技术研发中心 | Preparation method of attapulgite clay adsorbent for degumming and decoloration of palm oil |
US20130267404A1 (en) * | 2010-12-31 | 2013-10-10 | María Lidón Bou Cortês | Method for preparing an aqueous clay paste and use thereof in the manufacture of ceramic materials |
CN108816007A (en) * | 2018-07-06 | 2018-11-16 | 兰州坤仑环保科技有限公司 | A kind of mineral agent of large-scale instrument and equipment packaging |
CN110681372A (en) * | 2018-07-05 | 2020-01-14 | 金昌红泉膨润土有限责任公司 | Method for preparing decoloring agent by using low-grade attapulgite clay raw ore |
CN115261356A (en) * | 2022-07-26 | 2022-11-01 | 浙江长安仁恒科技股份有限公司 | Phytase production-increasing agent produced by clay fermentation and preparation method thereof |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2363876A (en) * | 1942-03-28 | 1944-11-28 | Attapulgus Clay Company | Improved fuller's earth and preparation thereof |
US2477386A (en) * | 1948-08-21 | 1949-07-26 | Attapulgus Clay Company | Method of improving the adsorbent and decolorizing properties of georgia-florida fuller's earth |
US3041238A (en) * | 1958-08-06 | 1962-06-26 | Minerals & Chem Philipp Corp | Method of preparing activated attapulgite |
US3953292A (en) * | 1974-02-01 | 1976-04-27 | Engelhard Minerals & Chemicals Corporation | Enzymes bound to heat-activated attapulgite clay |
-
1981
- 1981-02-25 US US06/238,272 patent/US4339352A/en not_active Expired - Lifetime
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2363876A (en) * | 1942-03-28 | 1944-11-28 | Attapulgus Clay Company | Improved fuller's earth and preparation thereof |
US2477386A (en) * | 1948-08-21 | 1949-07-26 | Attapulgus Clay Company | Method of improving the adsorbent and decolorizing properties of georgia-florida fuller's earth |
US3041238A (en) * | 1958-08-06 | 1962-06-26 | Minerals & Chem Philipp Corp | Method of preparing activated attapulgite |
US3953292A (en) * | 1974-02-01 | 1976-04-27 | Engelhard Minerals & Chemicals Corporation | Enzymes bound to heat-activated attapulgite clay |
Non-Patent Citations (1)
Title |
---|
W. S. W. McCarter et al., "Thermal Activation of Attapulgus Clay", Industrial & Engineering Chemistry, vol. 42, pp. 529-533, 1950. * |
Cited By (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5413978A (en) * | 1993-11-30 | 1995-05-09 | Engelhard Corporation | Catalytically inert particles for blending with petroleum cracking catalyst |
CN1052210C (en) * | 1994-11-06 | 2000-05-10 | 张义纲 | Process for preparing activated bleaching clay from attapulgite clay |
US5935623A (en) * | 1998-01-15 | 1999-08-10 | Milwhite, Inc. | Use of thermally treated clays in animal feeds |
WO2001034295A1 (en) * | 1999-11-12 | 2001-05-17 | Engelhard Corporation | Sorbent, method of making the sorbent, and method of using the sorbent in fixed bed applications |
CN101733076B (en) * | 2009-12-31 | 2011-12-14 | 四川大学 | Modified attapulgite adsorbent for tannery wastewater treatment and preparation method thereof |
US20130267404A1 (en) * | 2010-12-31 | 2013-10-10 | María Lidón Bou Cortês | Method for preparing an aqueous clay paste and use thereof in the manufacture of ceramic materials |
EP2660221A1 (en) * | 2010-12-31 | 2013-11-06 | Bou Cortés, María Lidón | Method for preparing an aqueous clay paste and use thereof in the manufacture of ceramic materials |
EP2660221A4 (en) * | 2010-12-31 | 2014-06-18 | Cortés María Lidón Bou | Method for preparing an aqueous clay paste and use thereof in the manufacture of ceramic materials |
CN102806063A (en) * | 2012-09-04 | 2012-12-05 | 中国科学院兰州化学物理研究所盱眙凹土应用技术研发中心 | Preparation method of attapulgite clay adsorbent for degumming and decoloration of palm oil |
CN110681372A (en) * | 2018-07-05 | 2020-01-14 | 金昌红泉膨润土有限责任公司 | Method for preparing decoloring agent by using low-grade attapulgite clay raw ore |
CN108816007A (en) * | 2018-07-06 | 2018-11-16 | 兰州坤仑环保科技有限公司 | A kind of mineral agent of large-scale instrument and equipment packaging |
CN115261356A (en) * | 2022-07-26 | 2022-11-01 | 浙江长安仁恒科技股份有限公司 | Phytase production-increasing agent produced by clay fermentation and preparation method thereof |
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